


in fidem

by wordstruck



Category: Haikyuu!!
Genre: Alternate Universe - Final Haikyuu Quest, Childhood Friends, Demon Oikawa Tooru, FHQ AU, Final Haikyuu Quest, Fluff, Knight Iwaizumi Hajime, M/M, Pre-Slash, Prince Oikawa Tooru
Language: English
Status: Completed
Published: 2018-07-20
Updated: 2018-07-20
Packaged: 2019-06-13 11:18:04
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,793
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15363447
Author URL: https://archiveofourown.org/users/wordstruck/pseuds/wordstruck
Summary: Later, Iwaizumi looks at Oikawa sitting across the bed from him, and says, “I’m going to be a knight one day.”Oikawa looks up from where he’d been reading, blinks out of a daze. Iwaizumi exhales sharply, nods, then stands up precariously on the mattress, hands clenched into fists at his sides.“If you’re gonna be king,” he continues, determined, “then I’m gonna be your knight. That way I’ll always be with you, and I can make sure nothing will happen.”The crown prince looks at him with wide eyes for a long moment, and Iwaizumi almost wavers. But then Oikawa’s face breaks into a big smile and he scrambles to stand, almost toppling from the bed in excitement.“You will?” Oikawa asks, and his expression is all lit up, like sunshine.Iwaizumi nods again, tilting his head up. “Promise.”





	in fidem

**Author's Note:**

> This is my piece for High Quest, a Final Haikyuu Quest zine ^ ^ I'm also posting it bc I don't have anything for Oikawa's birthday (too busy huhu) and since we're allowed to put these up now, I figured today was as good a time as any. Presenting the pre-canon AU of knight!Iwaizumi and demon prince!Oikawa!
> 
> Carrie (the FHQ Zine mod) also made [a gorgeous accompanying illustration](https://twitter.com/carriecmoney/status/1012477534884257793) for the fic, which you should definitely check out and love.

* * *

 

The capital city of Miyagi is alive with color for the Festival of Dragons - reds and purples and yellows, and a sea of turquoise, the pennants and flags of the royal house flying high in the breeze. For the people, it means a week of festivities and merriment, means abundance. Travellers from across the nation flock to the city -- the traders of Fukurodani and Wakunan, the high houses of Shiratorizawa and Inarizaki -- turning an already-bustling city into one of the busiest in the country.

Iwaizumi loves it.

He doesn’t get much time off, admittedly; as the son of the royal blacksmith, he’s needed in his father’s workshop -- the jousting and swordfight tournaments during the festival mean that the smithy is busier than usual. But he steals away from time to time, to watch the performers in the streets, or buy some of the festival food, or wander around with his friends. They run through the streets, occasionally meeting up with other children, throwing themselves into the revelry around them.

And sometimes -- just sometimes, and only if he’s lucky -- he spends the afternoon with Oikawa.

The crown prince is rarely allowed outside the castle during the festival, but Oikawa has more than enough to preoccupy himself inside the royal complex. Performers from all over the nation come to put on shows for the royal house, and there are feasts day in and day out, with a steady stream of visitors. When they can get away with it, Oikawa invites Iwaizumi to join in, to watch the magic show put on by the travelling mages from Nekoma or to have lunch with him on the sprawling castle grounds. And sometimes, in the middle of things, Oikawa will look at Iwaizumi and grin, take Iwaizumi’s calloused hand in his and drag him through the castle, up the back ways and servants’ staircases. There, they can while away the hours together, reading and talking and falling asleep together in the library.

Those afternoons, they’re Iwaizumi’s favorites.

Today, however, is a little different.

He’s slipped out of the smithy for a bit to see if there’s something to eat in the kitchens. Iwaizumi’s peeking around the heavy kitchen doors when he hears someone behind him.

“Psst -- Iwa-chan.  _ Iwa-chan. _ ”

Iwaizumi already knows who it is without looking. There’s only one person in the whole of Miyagi who calls him that.

Oikawa is peering at him from around the corner at the end of the hall, presumably having stolen down the servants’ staircase to come here. Instead of the elaborate garb he’s usually made to wear during the festival, the crown prince has changed into a nondescript grey tunic under a plain brown cloak. It’s the small black horns poking out of a riot of brown curls that give him away.

“Aren’t you supposed to be upstairs?” Iwaizumi asks, turning away from the kitchen.

“I snuck out.” Oikawa grins and beckons him over. “Come on, Iwa-chan, let’s go.”

Iwaizumi stops a few paces away, brow furrowed. “Go where?”

The prince shrugs, lips twisting into an impatient pout. “Just follow me.”

Iwaizumi hesitates for all of a moment, then he nods.

“Okay.”

 

The two of them take the corridors at the back of the castle, giggling and scurrying into alcoves whenever they hear voices or footsteps. Oikawa eventually leads them to the east exit, by the stables; it opens directly to the Merchants’ Quarter and the Tama Plaza, where plenty of vendors have set up shop. Iwaizumi comes to a stop when he realizes that Oikawa means to take them  _ outside.  _

Oikawa slows to a halt a few steps ahead, looking back at him in confusion.

“You didn’t say we were  _ leaving, _ ” Iwaizumi says, frowning. Sneaking away with Oikawa to somewhere in the castle is one thing; going out into the main city is something else entirely, and especially with the crown prince in tow, even disguised. He may only be twelve years old, but Iwaizumi understands that much.

Oikawa gives him a  _ look  _ and huffs. “It’ll be  _ fine _ . I just want to see what it’s like out there.”

Iwaizumi pinches his lips shut, uncertain. He  _ does  _ want to go outside and see the rest of the festival, and he knows that Oikawa must be sick of being stuck inside the castle walls when everything is happening just outside them, but-- “What if something happens?”

His friend cocks his head, bemused. “But you’ll be with me.”

And that -- Iwaizumi blinks at him, taken aback. “Me?”

“Yeah.” Oikawa hops forward and sticks out a hand. “So long as you’re around, nothing bad will happen.”

And it’s -- the way he says it, so blithely certain. The way Oikawa holds out his hand, like he’s sure Iwaizumi will take it. A simple, unwavering faith. 

Something warm unspools in Iwaizumi’s chest.

Tentatively, he takes Oikawa’s hand, glancing over his shoulder in minor trepidation. But Oikawa just smiles and tugs him along, ducking around the stables and waiting until the guards have turned their backs before making a run for it.

One of the guards calls after them, but no one gives pursuit. Still, they don’t stop running until they’re several blocks away, hidden in one of the side streets. They stagger around the corner, breathless with laughter and exertion. Iwaizumi starts hiccuping, which sets them off even more.

Oikawa’s still holding his hand.

When they’ve managed to compose themselves, Iwaizumi takes stock of where they are. Given their proximity to the staircase leading to the upper city level, he guesses they’re near the edge of the Merchants’ Quarter. The sounds from the plaza carry through the air along with the tempting smells of different kinds of food.

The two of them look at each other, then grin. Then hand in hand, they steal through the streets and into the festival around them.

 

Much later -- after they’ve had a time of it eating all kinds of food and watching the Johzenji sword dancers, and have snuck back into the castle; after they get a scolding from the crown prince’s attendant and a long-suffering (if fond) sigh from the Grand King; after Iwaizumi sneaks out of his family’s quarters in the castle to find Oikawa in his bedroom -- later, Iwaizumi looks at Oikawa sitting across the bed from him, and says,

“I’m going to be a knight one day.”

Oikawa looks up from where he’d been reading, blinks out of a daze. Iwaizumi exhales sharply, nods, then stands up precariously on the mattress, hands clenched into fists at his sides.

“If you’re gonna be king,” he continues, determined, “then I’m gonna be your knight. That way I’ll always be with you, and I can make sure nothing will happen.”

He says it with all the assurance of youth and a stubborn resolve. He’s had most of the evening to think about it, and if Oikawa believes in him so much then he’s going to live up to that faith. Oikawa will be the Grand King one day, and Iwaizumi intends to be right beside him when the time comes.

The crown prince looks at him with wide eyes for a long moment, and Iwaizumi almost wavers. But then Oikawa’s face breaks into a big smile and he scrambles to stand, almost toppling from the bed in excitement.

“You will?” Oikawa asks, and his expression is all lit up, like sunshine.

Iwaizumi nods again, tilting his head up.

“Promise.”

  
  


The capital city of Miyagi is alive with color for the Festival of Dragons; Iwaizumi thinks he’ll never get tired of this sight. All around him -- on the walls, from the ceiling, even on his clothes and armor -- is the turquoise of the royal house. He fidgets with the kerchief tied around his arm, a favor from the crown prince himself.

_ So my champion will have good luck in his jousts,  _ Oikawa had said, smirking, as he’d tied it around Iwaizumi’s rerebrace. Still, his fingers had been gentle, smoothing out the fabric so the royal insignia showed clearly.

The prince’s champion. Iwaizumi supposes that  _ is  _ what he is now, after he’d won all his jousts and fights and earned the right to be named to the royal guard. And not just any position, besides.

“Sir.” Iwaizumi turns to find one of the castle attendants holding open the door to the main castle hall. “It is time.”

Deep breath, and walk forward.

The throne room is full of people -- all the guests, members of nobility and military, and the winners of the other tournaments. The attendant leads him to the head of the room, where the Grand King stands waiting. A little ways behind him, Oikawa stands in front of the right-hand throne, a striking figure in full royal garb. Their eyes meet across the room, and when Iwaizumi gives him a small wink, Oikawa’s lips curl up in a subtle smile.

He stops a few paces away from the Grand King, dropping to one knee and placing his right fist on his chest in salute.

“Your Majesty,” Iwaizumi says, bowing his head.

He can’t look up, but Iwaizumi knows the king is moving forward, Sword of Seijoh in hand. He can sense the king coming to a stop in front of him, commanding the attention of the whole room.

“Iwaizumi Hajime, you come before the presence of the royal house to swear yourself in loyalty and service to the crown, the city, and its people. Let everyone in this room hear your words and bear witness to your oaths.

“Do you swear yourself to the people, to act in their needs and their interests?”

His fist clenches, presses against his cuirass. “I swear.”

“Do you swear yourself to the crown, to carry out its wishes and defend it in its need?”

“I swear.”

“And do you swear yourself to the crown prince, to follow him and protect him, to the very last of your life?”

Iwaizumi closes his eyes. Takes a steadying breath. Answers in a steady, ringing voice.

“I swear.”

The sword touches first his right, then his left shoulder; when it is lifted, Iwaizumi raises his head with it. And while protocol dictates he looks at the king, Iwaizumi can see Oikawa in his peripheral vision, a grounding force in everything.

“Rise, Iwaizumi Hajime, Knight to the Crown Prince. Long may you serve him, as long as he live.”

Iwaizumi stands as the king steps back, and this time he does meet Oikawa’s eyes across the steps to the thrones. And while the crown prince’s expression is one of carefully schooled complacency, Iwaizumi can still see the fondness crinkling the corners of his eyes, the pride.

Iwaizumi raises his head high, standing tall before the man he’d just pledged his life to protect.

He’s kept his promise.

**Author's Note:**

> Thank you for reading!! ^ ^ Come say hi on social media – I'm [@okw_tr](https://twitter.com/okw_tr) on Twitter and [okwtr](https://okwtr.tumblr.com) on Tumblr. You can check there for ways to support my writing!


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